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Passive House in detail Because Passive House standards are so well defined and because Passive House modeling software—known as the Passive House Planning Package—predicts home performance, the path to certification is clear. Meet the benchmarks, and you’ll obtain the certification. The standards focus on three building attributes: airtightness, Btu consumption, and energy usage. AIRTIGHTNESS The Passive House standard requires the home to be tested at or below 0.60 air changes per hour (ACH) at 50 pascals (Pa)—122cfm at 50 Pa in this house. That’s tight, considering the typical code-built house might have a tightness range of 3.0 to 7.0 ACH at 50 Pa. BTU CONSUMPTION Passive House standards require the annual heating and cooling consumption to be below 4755 Btu per sq. ft. annually. A code-built house can have a consumption rate nearly 10 times that amount. windows that met Passive House standards but were different from what the homeowner had originally wanted. Chasing the Passive House plaque is a goal that should be considered carefully and talked about throughout the design phase to avoid too much compromise. Initially, I think Passive House certification should be a goal written in pencil. If the client is interested solely in a very energy-efficient house and not necessarily the plaque on the wall, a house that reaches 80% or 90% of the standard is less costly to build and still far better performing than any typical code-built house in the United States. It’s even better than www.finehomebuilding.com those houses that are built to other greenbuilding standards. We were committed to the standard and understood that due to the limited number of comparable, exemplary projects, there was limited knowledge within the industry on how to construct a Passive House. Because of that shortcoming, our approach to the project had to be planned carefully. Organized from the start I’ve developed a simple two-phase philosophy when it comes to designing highperformance houses: I aim to design a house that, when built correctly, converts energy as ENERGY USAGE The maximum energy use in a Passive House, not counting any photovoltaic offset, must not be greater than 11.1kwh per sq. ft. Building codes don’t have energy-use provisions, but it’s estimated that the average American house consumes electricity at a rate of 958kwh per month, or 11,496kwh per year. SPRING/SUMMER 2012 77